Nous avons fait cette réservation il y a deux semaines, parce qu’aucune chambre double n’était disponible avant.

Nous avons fait is in the passé composé, which is one of the main French past tenses. It shows that the action of making the reservation happened at a specific moment in the past.

• nous faisons = we do / we are doing
• nous avons fait = we did / we made
• nous avons réservé = we reserved / we booked

In this sentence, faire une réservation means to make a reservation, which is a very natural French expression. French could also say nous avons réservé, but the sentence you have uses the noun réservation with the verb faire.

French often uses a verb + noun expression where English might prefer a single verb.

So:

• faire une réservation = to make a reservation
• réserver = to reserve / to book

Both are possible, but faire une réservation is completely normal and idiomatic. It is similar to other French expressions like:

• faire un voyage = to take a trip
• faire une promenade = to take a walk

So this is just a common French way of expressing the idea.

Here, il y a deux semaines means two weeks ago.

Literally, il y a often means there is / there are, but in time expressions it can mean ago.

Examples:

• il y a deux jours = two days ago
• il y a un mois = a month ago
• il y a deux semaines = two weeks ago

So the sentence means that the reservation was made two weeks before now.

French often places time expressions after the main verb phrase.

So:

• Nous avons fait cette réservation il y a deux semaines.

This is very natural French word order: subject + auxiliary + past participle + object + time expression

English often does something similar:

• We made this reservation two weeks ago.

You could move time expressions around in some contexts, but this placement is the most straightforward and natural here.

Because réservation is a feminine singular noun.

French demonstratives agree with the noun:

• ce = masculine singular
• cette = feminine singular
• ces = plural

So:

• ce livre = this book
• cette réservation = this reservation
• ces chambres = these rooms

You use cette because réservation is feminine.

It is the same word: parce que = because.

French shortens que to qu’ before a vowel sound for ease of pronunciation:

• parce que la chambre...
• parce qu’aucune chambre...

So parce qu’ is just parce que followed by a word beginning with a vowel, in this case aucune.

Aucune means no, not any, or more literally not a single when used before a feminine singular noun.

• aucun = masculine singular
• aucune = feminine singular

Since chambre is feminine, French uses aucune chambre.

Even though English often says no double rooms in the plural, French commonly uses the singular after aucun / aucune:

• aucune chambre = no room / not a single room
• aucun problème = no problem / not a single problem

So aucune chambre double literally suggests not a single double room.

Because aucune already carries the negative meaning.

French often uses ne with negative words like aucun, personne, rien, etc.

So:

• Aucune chambre double n’était disponible. = No double room was available.

You do not usually add pas here, because that would be redundant or non-standard in normal French.

Think of it like this:

• ne ... pas = ordinary negation
• ne ... aucun(e) = negation with no / not any

French often uses the imparfait for a state, condition, or background situation in the past.

Here, being available is a state:

• aucune chambre double n’était disponible = no double room was available

This describes the situation that existed at that time. It is background information explaining why they made the reservation two weeks ago.

If you used a été disponible, it would sound more like a completed event or a change, which is not the main idea here.

So the contrast is:

• Nous avons fait → completed action
• n’était disponible → background state at that time

That combination is very typical in French storytelling and explanation.

Because it agrees with aucune chambre double, which is grammatically singular.

Even though the meaning in English may feel plural (no double rooms), the French structure is singular:

• aucune chambre double = singular
• therefore disponible = singular
• and the verb était = singular

So the grammar is perfectly consistent: Aucune chambre double n’était disponible.

If the subject were plural, the adjective and verb would also be plural.

In French, many adjectives come after the noun, and double does here:

• une chambre double = a double room

This is just the normal position for this adjective in this expression.

Compare:

• une chambre simple = a single room
• une chambre double = a double room

So you should learn chambre double as a set phrase.

Here, avant means something like before that, earlier, or any earlier than that.

In context:

• ...n’était disponible avant means
• ...wasn’t available before then / any earlier

It refers to an earlier time than the reservation date. In other words, they made the reservation two weeks ago because there had been no double room available any sooner.

French often uses avant in this short way when the missing idea is understood from context.

This is because ne becomes n’ before a vowel sound.

So:

• ne était → n’était
• que aucune → qu’aucune

This happens very often in French and is called elision.

Examples:

• je n’ai pas
• il n’est pas
• qu’elle
• l’hôtel

It is purely a spelling and pronunciation rule; the meaning does not change.

Yes. A very natural simpler version would be:

• Nous avons réservé il y a deux semaines parce qu’aucune chambre double n’était disponible plus tôt.

This means almost the same thing.

The original sentence is slightly more formal or explicit because it says we made this reservation instead of simply we booked. Also, avant and plus tôt are close here, though plus tôt may be a bit clearer for some learners.

So the original is correct and natural; it is just not the only possible way to say it.